Refrigerating apparatus and method



Patented Dec. 25, 1928. p I UNITED STATES PATENT OFFICE.

THOMAS IB. SLATE, on NEW YORK, 1v. Y.,AssIe1von, BY MESNE ASSIGNMENTS, 'ro

AMERTGAN PATENT$ DEVELOPMENT CORPORATION, OF NEW YORK, N. Y., A COR- PORATION OF DELAWARE.

nEraIeEa TInd APPARATUS AND METHOD.

Original application filed January 10, 1924, Serial No. 685,482. Divided and this application filed September 2?, 1924. Serial No. 740,163.

My present invention relates more particularlyto refrigerating perishable products by means of frozen carbon dioxide enclosed in a suitably insulated container located within the refrigerator so that its insulated walls absorb heat from the atmosphere within the refrigerator and apply said heat tothe frozen carbon dioxide which absorbs it as latent heat producing a corresponding amount of intensely cold carbon dioxide gas without any intermediate liquid state, such gas bein discharged into the refrigerator atmo-sp ere. Various forms of apparatus for this purpose are set forth in my Patent No. 1,511,306, granted Oct. 14, 1924, on my application, Se-

rial No. 685,482, filed January 10, 1924, of

which this application is a division.

The divisional subject matter of this present application concerns the special form of the apparatus wherein a container for the carbon dioxide ice is located in a refrigerator car or the like, in an upper part thereof, with its upper surface near but substantially below the ceiling. Two such equipments are shown in said prior application, but the present form is the one adapted to be charged with a largequantity of carbon dioxide snow or ice previously manufactured elsewhere.

In the description in said prior application I have explained that this equipment may be supplied with an outlet pipe whereby a container chamber in one end of the car has its outlet connected for discharge of the refrigerant gas in the remote end of the car. I find that discharging the refrigerant gas at a point remote from the heat absorbing surfaces of the container has many advantages.

The amount of heat absorption (refri eration) afforded by heat absorption throug the outer surfaces of the container is well known to be approximately one-half the refrigerant value of the ice, the other'half being in the gas which results from the heat absorption. Hence, by the above described arrangement, equal refrigerant values are applied at each end of the car by a single container at one end thereof. Moreover, this arrangement romotes a. stagnant condition of the 'atmosp ere within the car. The intensely cold gas discharged at one end flows downward, to the bottom of the car where it displaces upward.

the ordina air, and also tjlireviousl'y dis charged an partially warm'e layers ofcar bon dioxide gas. On the other hand, the heat absorption at the surface of the container is much less intense and takes effect on atmosphere that is lighter because its chilling is far less intense, and also because it is atmosphere naturally drawn from the upper part which is warmest and contains the most air.

Consequently the atmospheric circulation at the surface of the container tends to be an Fig. 3 is a perspective View of the snow chamber 22; and

Fig. is a perspective view of a suitable cover for the same.

Referring to Figs. 1 and 2,I provide a snow chamber 22' for any chamber 20, to be refrigerated, such as'a refrigerator car. The

snow chamber 22 is supported on a suitable bracket 21. The chamber 22 is provided with or formed of insulating material which may be balsa wood. This chamber is used as the lnsulated chamber for the refrigerant 26', which may becarbon dioxide either as snow or as ice and which may be manufactured elsewhere and delivered to the chamber to' be refrigerated. I provide a suitable removable cover 34 on chamber 20 and a removable cover 31 on snow chamber 22, so that the space 26 is readily accessible for filling when needed. As the snow or ice 26 reverts to a gaseous state, it may be piped in any suitable manner to any desired part of the chamber 20, as by pipe 28, having its outlet 29 in the far end-of said chamber.

Fig. 3 shows an enlargedview-of chamber liquid carbon dioxide, is porous and-light,

but may be easily compressed to bricks of density much greater than water ice, a cubic foot of the carbon dioxide ice weighing approximately 100 lbs. Such carbon dioxide ice occupies about half the space and is also about twice as effective per pound as water ice, making it especially valuable for refrigerator cars where space and weight are both expensive. V

As stated in my' said prior application, it is quite commonly known that carbon dioxide has great preserving qualities, as it is one of the most inert gases known and, being absolutely free of all bacteria and other elements, causing deterioration of all perishable prod ucts, it causes them when completely immersed in the pure gas to maintain their present state of preservation for a very considerable length of time, and any product that has its pores com letely filled with carbon dioxide practical y regardless of temperature, so that a combination of sli ht refrigeration and complete exclusion o atmospheric air will preserve perishable products longer and more completely than any other type of refrigeration; Pure carbon dioxide has an aflinity for moisture also that will prevent mold and other damaging effects caused by moisture.

This fact is especially valuable in shipping grapes and other small fruits that mould very easlly from the moisture of ordinary waterice refrigeration.

With the apparatus shown in Figs. 1 and 2, it will be evident that the container 22 can have its capacity suitably proportioned to the total capacity and contents of the chamber 20 and can have an amount of insulation necessary for the extended refrigeration desired and to prevent such over refrigeration as would be damaging to the products to be refrigerated. Such an appa ratus would keep the car cool enough for many purposes, even with the temperature range far enough above freezing to avoid all danger of freezing even under extreme conditions. 1

In all cases, the heavy intensely cold gas volatilized by heat absorbed through the walls of the container at one end of a car will escape as formed through thepipe 28 and outlet 29 in the upper part of the other end of the car. From the outlet, the gas will flow downward with very little diffusion, displacing the air upward and thus enveloping and preventing deterioration of the perishable products. At the same time ,,the frigeration effect due to heat absorbed by the container walls at the other end of the car will be more or less localized because'the temperature differences created are so very much smaller and because the atmosphere operated upon is primarily warmer and has a greater; content of ordinary air.

I claim:

as will e preserved from decay 1. The method of refrigerating material within a chamber which includes establishingseparate downflow currents of cooling medium in parts of the chamber remote from one another, the downflow in the first or primary region consisting entirely of the atmosphere of the chamber and the downflow in a second region consisting mainly of carbon dioxide gas; said first or atmospheric circulationbeing induced by enclosing frozen carbon dioxide in an air-tight imperfectly insulating container, whereby the cooling in said region is entirely by absorbing heat from the atmosphere through the outer surface of said air-tight imperfectly insulating container; permitting the carbon dioxide gas to escape from the container by overflow through a high level outlet at a pressure so low that no further liquid or solid can be formed by expansion, whereby said gas first displaces all of the air in said container and then itself escapes as formed; conducting the expelled air and afterwards the pure gas so formed to said remote region of said chamher and then permitting it to escape and flow downward by gravity to thereby establish said gas and air downflow in said remote region. Y

2. The method of refrigerating material within a chamber which includes establish-.

ing separate downflow by gravity of cooling medium in parts of the chamber remote from one another, the downflow in the first or primary region consisting entirely of the atmossaid air-tight imperfectly insulating. con-y.

tainer; permitting; to ,escape from t e container by overflow through ahigh'level outlet at a pressure so low that no further li uid or solid can be formed by expansion, w ereb said gas first displaces all of the air in said container and then itself escapes as formed; conducting the expelled air and afterwards the pure gas so formed to said remote region of said chamber and then permitting it to escape at a high level and flow downward by gravity a considerable distance by gravity to thereby establish said gas and air downflow in said remote re 'on. p

3. A re rigerajgor for refrigerating perishable products, a container enclosing at a proximately atmospheric pressure a sup y of frozen carbon dioxide insulated from ut means for discharging the resultant cold gas the carbon dioxide gas' into a part of said atmosphere remote from said container.

4. A refrigerator of substantially greater length than width for refrigerating perishable products comprising a container means enclosing a supply of frozen carbon dioxide located in and deriving heat from the upper part of the atmosphere near one end of the refrigerator and means permitting discharge of-the resultant cold gas into a portion of said atmosphere horizontally remote from said container means; the insulation of the container means being substantial so that the normal temperature diiferential between said atmosphere and the heat absorbing surfaces of the container, will be relatively small.

Signed at New York city, in the county of New York, and State of New York, this 23rd day of September, A. D. 1924.

THOMAS B. SLATE. 

